PARIETAL REGION IN THE PRIMATE BRAIN 333 



the Querfurche becomes associated with the temporo-occipital 

 (inferior temporal) group of sulci. It is clear that further inves- 

 tigation of this region is necessary before any definite statements 

 can be made. 



The same might be said of the small sulcus frequently found 

 within the angular area, 39, the sulcus intermedius secundus of 

 Eberstaller. 



One more sulcus, or system of sulci, remains to be considered 

 The sulcus praelunatus, or better occipitalis lateralis, is an axial 

 folding of a forward extension of the peristriate area. Imme- 

 diately in advance of this and forming in a way a continuation of it 

 is the " visuo-auditory " band of Elhot Smith, connecting the 

 peristriate and superior temporal areas. It is not found by Brod- 

 mann but would occupy the uppermost part of the area 37, 

 between it and area 39. It is the axial folding of this band, in 

 Brodmann's chart this would occur between areas 37 and 39, 

 particularly common in the human brain which constitutes the 

 temporal-parietal sulcus. 



The fissural pattern within the occipital region behind the 

 lunate, and its significance has been fully elucidated elsewhere 

 and we shall not consider the question further. 



In attempting to understand the brain of man, and the same 

 considerations hold to a lesser degree for that of the higher An- 

 thropoids, one must constantly bear in mind the fact that one 

 is dealing with individual cases, cases subject to individual varia- 

 tion to an extent not yet determined for any single species, homo 

 sapiens not excepted. If variability is ever disconcerting it is 

 here, for one has to reckon with a variability of the most subtle 

 and elusive character, occurring as it does in the last and highest 

 product of evolution where the range and complexity of variation 

 is so great and our knowledge of its structural and functional man- 

 ifestations, for even a single case, so slight. Bearing this in mind 

 and remembering that we must interpret the foldings of the cor- 

 tex in the light of our knowledge of the structure of that cortex, 

 we may consider briefly certain conditions in man. It will be 

 evident that with the knowledge at our disposal at present we 

 can only hope to approximate the truth in our conception of the 



